Aircraft propulsion systems may use an inlet diffuser to govern the introduction of ambient air into the aircraft engine. To reduce the drag forces created by an inlet diffuser, and to allow the inlet diffuser to be more efficiently integrated into the aircraft design, some current aircraft propulsion systems use high aspect ratio inlets that have a very wide opening which transitions to a circular engine face.
One important role of an inlet diffuser is to prevent boundary layer air from disrupting engine performance. Boundary layer air can cause total pressure recovery loss and total pressure distortions which can cause an engine to stall. To prevent this, some systems use a boundary layer diverter to prevent boundary layer air from entering the inlet diffuser. However, boundary layer diverters can reduce the aerodynamics of an aircraft, which slows down the speed and efficiency of an aircraft. Therefore, it is desired to have a new inlet diffuser for jet engines that prevents boundary layer air from disrupting engine performance while only minimally affecting the aerodynamics of the aircraft.